Object Object (JavaScript)

Provides functionality common to all JavaScript objects.

obj = new Object([value]) 

obj

Required. The variable name to which the Object object is assigned.

value

Optional. Any one of the JavaScript primitive data types (Number, Boolean, or String). If value is an object, the object is returned unmodified. If value is null, undefined, or not supplied, an object with no content is created.

The Object object is contained in all other JavaScript objects; all of its methods and properties are available in all other objects. The methods can be redefined in user-defined objects, and are called by JavaScript at appropriate times. The toString method is an example of a frequently redefined Object method.

In this language reference, the description of each Object method includes both default and object-specific implementation information for the intrinsic JavaScript objects.

The Object Object was introduced in Internet Explorer before Internet Explorer 6. Some members in the following lists were introduced in later versions.

The following table lists properties of the Object Object.

Property

Description

constructor Property

Specifies the function that creates an object.

prototype Property

Returns a reference to the prototype for a class of objects.

The following table lists functions of the Object Object.

Function

Description

Object.create Function

Creates an object that has a specified prototype, and that optionally contains specified properties.

Object.defineProperties Function

Adds one or more properties to an object, and/or modifies attributes of existing properties.

Object.defineProperty Function

Adds a property to an object, or modifies attributes of an existing property.

Object.freeze Function

Prevents the modification of existing property attributes and values, and prevents the addition of new properties.

Object.getOwnPropertyDescriptor Function

Returns the definition of a data property or an accessor property.

Object.getOwnPropertyNames Function

Returns the names of the properties and methods of an object.

Object.getPrototypeOf Function

Returns the prototype of an object.

Object.isExtensible Function

Returns a value that indicates whether new properties can be added to an object.

Object.isFrozen Function

Returns true if existing property attributes and values cannot be modified in an object and new properties cannot be added to the object.

Object.isSealed Function

Returns true if existing property attributes cannot be modified in an object and new properties cannot be added to the object.

Object.keys Function

Returns the names of the enumerable properties and methods of an object.

Object.preventExtensions Function

Prevents the addition of new properties to an object.

Object.seal Function

Prevents the modification of attributes of existing properties, and prevents the addition of new properties.

The following table lists methods of the Object Object.

Method

Description

hasOwnProperty method

Returns a Boolean value that indicates whether an object has a property with the specified name.

isPrototypeOf method

Returns a Boolean value that indicates whether an object exists in another object's prototype hierarchy.

propertyIsEnumerable method

Returns a Boolean value that indicates whether a specified property is part of an object and whether it is enumerable.

toLocaleString method

Returns an object converted to a string based on the current locale.

toString method

Returns a string representation of an object.

valueOf method

Returns the primitive value of the specified object.

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